Transcript M & M conference 10/18/02

M & M conference 10/18/02
Andrea Balazs M.D.
Dept. of Pediatrics
Neural Tube Defects
Neurulation
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Brain and sp.cord formation
on the dorsal aspect of the embryo
3rd – 4th w of pregnancy
Mesoderm induce the formation of the neural plate
from the ectoderm ~18th days of gest. – neural
tube - ant. closure 24th day –post.closure 26th day
Caudal neural tube formation 28-32nd day
from caudal cell mass - vacuoles - coalesc
contact with the central canal - canalization
and differentation
Neural tube defects
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Craniorachischisis
Anencephaly
Encephalocele
Myelomeningocele
Craniorachischisis totalis
Total failure of neurulation
Neural plate like structure, no overlying
skeleton or skin, occurs on 20-22nd day
abortion
Anencephaly
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Failure of the anterior neural tube closure
Degenarated mass of neurons, glia, vessels
Froglike appearance
Occurs on 24th day
Polyhydramnion
75% stillborn or die during the neonatal period
Rates of occurrence 0.2/1000 live births
Anencephaly
• 4x as frequent in females than in males
• Expl.neurulation takes longer, longer
vulnerable period
Encephalocele
• Herniation of the brain tissue
• Location: occipital 70-80%, frontal / temporal /
parietal – less common
• Protruding mass - occipital lobe / cerebellum
• 50 % complicated with hydrocephalus
• low occipital or high cervical EC combined with
vertebra, skull base and lower brain stem anomaly
compose Arnold - Chiari III
Encephalocele
• Partial or complete agenesis of corpus
callosum
• Venous drainage anomaly
• Occures before 26th day
• EC associated with visual
problem,microcephaly, MR and seizure
• Meningocele – 10 - 20%, no neural
element,usually no neurologic deficit
• Outcome more favorable in anterior EC
(mortality 0% vs 45%, nl.outcome 42% vs
14%)
• Thx: surgery
Myelomeningocele
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Failure of the posterior neural tube closure
80% in the lumbar region
variable dermal covering
dorsal displacement of the neural tissue, CSF
leakage, sac formation
• neural plate or neural tube-like structure,
raw,velvety,flat
• ventral part of the cord less affected
• Axial skeleton deficiency: lack of fusion or
absence of the vertebral arches, widened spinal
canal
Myelomeningocele
• Onset no later than 26th days
• Overall incidence 1:1000 live births ’89
• Risk of recurrence 3% after one affected
child, 10% with 2 previous abnormal
pregnancies
Myelomeningocele
Clinical features:
• Lesion itself
• disturbances of neurological function pending on
the level (motor, sensory, and sphincter function)
• Low sacral lesions: bowel and bladder
incontinence and anesthesia in the perineal area
• Lesions below S1 able to walk unaided
• Lesion above L2 wheelchair, later scoliosis, as
well
Myelomeningocele
• Intermediate/midlumbar lesion L3 – L4 or L5
• Flaccid paralysis of the LE’s, absence of deep
tendon reflexes
• Lack of response to touch and pain
• Clubfeet, hip subluxation
• Continuous urinary dribbling and relaxed anal
sphincter
• ambulatory or primarily ambulatory with braces
or cruthces
Myelomeningocele
• Deterioriation to a lower level of ambulatory
function than that expected from segmental level
over time
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Hydrocephalus incidence 60% vs 90%
HC > 90% ventriculomegaly in 95%
AF, sutures status
S/s of hydrocephalus is overt by 2-3 weeks
of life
• Arnold –Chiari II malformation
accompanies thoracolumbar - lumbosacral MMC
Sequence of events
MMC - CSF leakage - lack of normal distension
of the ventricles - small posterior fossa - inferior
displacement of the medulla, IV th ventricle and
cerebellum
elongation, thinning of the medulla and pons
kinking of the cervical cord
obstructed CSF flow - aquaeductus sten. and
hydrocephalus
Clinical features associated with A-C II
malformation:
• brain stem dysfunction –feeding disturbances (reflux,
aspiration), dysphagia, apnoe, stridor, cyanotic spells
onset at 3.2 months
causes: brain stem malformation and displacement affects the
cranial nerves and nuclei
these structures under compression from the
hydrocephalus and the increased ICP
ischemic and hemorrhagic necrosis of the brain stem from
the disturbed arterial architecture and caudally displaced
vertebrobasilar circulation
Other anomalies of the CNS associated with
MMC:
Abnormal cortical development:
Microgyria 55-95%
intellectual deficits and seizures
Impaired neuronal migration
Falx cerebri hypoplasia, septum pellucidum
Anomalies
Cerebellar dysplasia
Management
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Prevention
Prenatal therapy
Human fetal surgery
Optimal means of delivery of the affected infants
-c/s vs vag. - paralysis level 3.3 segments below
the anatomical level of the lesion to compare with
1.1 for babies delivered vag. - amb. or wheelch.
• Postnatal surgery - early closure - proph. Abx –
VP shunt placement
Management
• Team approach – specialties
PE :
• Correlate the functional level (motor, sensory and
sphincter function and reflexes ) to the level of
anatomic lesion
• Neurologic dysfunction correlates with the level
of the spinal cord lesion
• Presence of anal wink and anal sphincter tone
suggest functioning sacral spinal segments,
prognostically important
• evaluate for other malformation
• Hydrocephalus – VP shunt – IQ better preserved
• Earlier shunt placement improves the cognitive
outcome - degree of ventriculomegaly in utero or
the size of the cerebral mantle during the 1st week
correlates with the subsequent intelligence
• Shunt complications - deleterious effect on
intellectual outcome
• Mean IQ – MMC + infected VP shunt 73 / vs
MMC + VP shunt w/o infection 95
• MMC w/out hydrocephalus mean IQ 102
Rare VP shunt complication
Migration of the VP shunt tip through the
patent processus vaginalis resulting in
scrotal hydrocele
Complications in MMC
Orthopedic problems
• Lower extremities lack innervation –
atrophied foot, knee, hip and spine
deformities – result from muscle imbalance,
abn. In utero positioning
• Hip dislocation/subluxation in 1 year
mostly with midlumbar MMC
• contractures
Complications in MMC
Urinary tract abnormalities
• Major cause of death after the 1st year
• > 85% MMC located above S2 associated with
neurogenic bladder
• Urinary incontinence and ureteral reflux
• Hydronephrosis, chronic pyelonephritis with renal
scarring and destruction, urosepsis
• Renal anomalies: agenesis, horseshoe k.,ureter
duplication
Spina bifida occulta
Neural lesions
• Myelocystocele –cystic dilatation of the central
canal of the caudal neural tube
• Diastematomyelia – diplomyelia – spinal cord is
bifid, occassionally separated by fibrous or bony
septum originating from the vertebra
• Lipomeningocele
• Epidermoid/dermoid sinus
• Tethered cord
• Meningocele (anterior, too)
• Agenesis of distal spinal cord
Complications in MMC
• Outcome of cortical function pending on the level
of lesion:
• Lumbar MMC nl. range of intelligence
• Reading and spelling o.k.
• Greatest deficit in arithmetic achievement and
visual – motor integration
• IQ >80 with lesion below S1
• IQ > 80 in 50% of pt. with thoracolumbar lesion
Spina bifida occulta
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Caudal locus L5-S1
Covered by skin
No neurological deficit
Undetected for years
Abnormal conus med. (prolonged) and
filum terminale (thickened)
• “Tetherd “ or fixed at their caudal end by
fibrous bands,lipoma, dermal sinus
Spina bifida occulta
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Vertebra abnormality 85-90%
laminar defects over several segments
Widened spinal canal and sacral deformities
Skin lesion 80% - hair tufts, dimples or
tracts, hemangioma, skin tag, cutis aplasia,
pigmented macula, sc. Mass, lipoma,
dermal sinus (epidermoid,dermoid cyst)
• 15-20% infants of diabetic mothers
Spina bifida occulta
Clinical aspect
• Neurological deficits appear later in infancy
• Delay in development of sphincter control,
in walking, asymmetry of legs or abn. feet
• Pain in the back or lower extremities
• Recurrent meningitis
• In older child: gait disturbance, foot
deformity, scoliosis, abnormal sphincter f.
Spina bifida occulta
Management
spine x – ray
spine US
if both nl. And no sy - only clinical F/U
if abn. - MRI
thx. – surgery in neonatal period to prevent
neuro.deficits
New things
Fetal surgery
• Goal: to prevent damage to the cord and prevent
complications related to the primary anomaly, to
restore or preserve neurologic function
• Done 28-30 w , via hysterotomy
• Theoretical advantage of FS: greater potential for
healing and regeneration in the fetus
• Results: no improvement in motor function
• Definite improvement in the cerebellar herniation
– A-C III regressed, less likely to require VP shunt
– nl.CSF circulation
New things
Fetal surgery
2 pt. at risk
Induction of early labor, preterm delivery,
infection, death
MMC is not lethal lesion
• Iatrogenic dermoid inclusion cyst in infancy
• Progressive neur. deterioriation for spinal cord
tethering
• Unknown, unforseen complication
Thank you for your attention
And
Than you for your help
Dr. Levin
Dr.Quattromani